Pronged darby



April 1, 1958 A. s WILLIAMS 2,828,619

PRONGED DARBY Filed May a, 1955 Allen '5. Williams IN VEN TOR.

United rates Patent PRONGED DARBY Allen S. Williams, Washington, D. C.

Application May 6, 1955, Serial No. 506,493

1 Claim. (Cl. 72-136) This invention generally relates to a darby and more specifically provides improved and novel structure in plasterers darbies for use in providing the proper key on the brown coat of plaster so that the finish coat of plaster will adhere thereto.

An object of the present invention is to provide a darby having generally an elongated blade of light metallic construction such as aluminum that is provided with a longitudinal reinforcing rib at the center thereof with a handle adjacent each end thereof for handling the darby.

Another important object of the present invention is to provide a plasterers darby having a plurality of depending projecting prongs at each edge of the plate for extending below the plane of the plate for forming grooves or serrations in the surface of the plaster being placed onto a building wall.

Yet another important object of the present invention is to provide a plasterers darby in accordance with the preceding objects wherein the darby is provided with a slightly rounded or convexed undersurface on the plate and provided with novel construction at the edges thereof for providing means for easily forming the depending projecting prongs thereon.

Other objects of the present invention will reside in its simplicity of construction, ease and efficiency of operation, light-weight, its adaptation for its particular purposes and its relatively inexpensive manufacturing cost.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

Figure l is a perspective view of the darby of the present invention;

Figure 2 is a longitudinal, vertical sectional view taken substantially upon the plane passing along section line 12-2 of Figure 1 illustrating the details of construction thereof and showing the relationship of the projecting prongs and the COIIVEKEd bottom surface of the plate;

Figure 3 is an enlarged perspective view illustrating the construction of the angulated recesses forming the depending prongs on the elongated plate; and

Figure 4 is a bottom plan view of the plate illustrating the positioning of the prongs thereon.

Referring now specifically to the drawings, it will be seen that the numeral generally designates the pronged darby of the present invention which includes an elongated plate or blade 12 which is relatively fiat and thin and constructed of light metal, such as aluminum or some similar type of material. The plate 12 is provided with an elongated longitudinal rib 14 along the longitudinal center line of the upper or back surface thereof. Adjacent one end of the plate 12 is an upstanding cylindrical handle member 16 secured to the longitudinal rib 14 by suitable securing means such as the screw fastener 18. Adjacent the other end of the plate 12 is an elongated wooden plate member 21) which forms a handle having apertures or bores 22 extending therethrough for receiving a screw-threaded fastener 24 which is in threaded engagement with a threaded socket 26 in the rib 14 and plate 12 wherein the plate 12 may be handled by a person plastering by utilizing the handles 16 and 20.

The bottom of the plate or the front working surface thereof is slightly convexed or rounded as designated by the numeral 28 for facilitating the movement thereof. The outer edges of the plate 12 are downwardly and outwardly inclined forming a bevel edge as designated by the numeral 30. The bevel edge is provided with a plurality of inclined depressions 32 which are struck downwardly thereby forming depending prongs or projections 34 which project beyond the surface 28 of the plate 12 wherein the projecting lugs 34 will engage and serrate a plaster surface for roughening the surface and forming grooves therein. By taking a suitable tool and forming the depressions 32 by striking a downward force on the inclined bevel edge 36, the lugs 34 will be formed substantially in the same manner as saw teeth are formed on a saw. Due to the metallic construction and the light weight of the darby 10, it may be moved about the wall surface being plastered thereby forming an effective key on the brown coat for adhering the finish coat thereto. Also, the darby 1d of the present invention is useful in forming plaster finishes with decorative arrangements of grooves or roughened surfaces.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention as claimed.

What is claimed as new is as follows:

A darby comprising an elongated light-weight metallic blade having a longitudinal reinforcing rib on the rear side thereof, longitudinally spaced handles attached to said rib, said blade having a smooth transversely convexed working surface, said blade having inclined beveled side edges extending in diverging relation towards said working surface, each of said beveled edges being provided with a plurality of closely spaced inclined notches by striking downwardly with a suitable tool thereby forming a series of depending lugs along each edge and terminating beyond the working surface for engagement with the plaster surface without tilting the blade about its longitudinal axis for scratching the plaster surface, the convex curvature of the working surface of the blade assuring contact of the center of the working surface with the plaster surface in advance of either side edge striking the plaster surface thereby forming a runner for the blade.

References Cited in the file of this patent UNITED STATES PATENTS 2,048,529 Williams July 21, 1936 2,578,163 Whalen Dec. 11, 1951 2,626,520 Whalen Jan. 27, 1953 

